Camping equipment, including a sleeping bag, should be light and compressible because a hiker who is also camping may have to carry the equipment a long distance. It will be appreciated that a sleeping bag does not provide heat, but merely serves to trap and retain the user's own body heat, so a sleeping bag must provide sufficient insulation to keep the user warm. The insulation in a sleeping bag is most effective when the loft (thickness, or height) is at its design maximum.
When a sleeping bag is used in a hammock the weight of the user compresses the insulation, thereby decreasing the loft and the insulating value of the bag, particularly at pressure points along contact with a support system, which is often either the ground or a hammock. Even at temperatures where the sleeping bag should have sufficient insulation to keep the user comfortable, the user often feels cold when using a conventional sleeping bag because the insulation between the user and the support system has been compressed. This reduction in the insulating value is especially noticeable when the underside of the sleeping bag may be exposed to wind, such as when the sleeping bag is used with a hammock. Thus, the compressed insulation represents dead weight for the user as it does not provide the desired warmth. As a result, if a sleeping bag is to be used with a hammock, the sleeping bag must have more insulation so that the resulting insulation value is still adequate when the insulation becomes compressed. This, however, results in a larger and heavier sleeping bag, which is not desirable when backpacking